Treatment of hydrocarbon oils



Aug. 14, 1934. 5 Y 1,970,283

TREATMENT OF HYDROCARBON OILS 1 Filed Feb. 8. 1932 20 T .Tiaaiz'ana fo Condemns e7 ll777lt la for fizfin for; oland 3 Jay,

Patented Aug. 14, 1934 TREATMENT OF HYDROCARBON OILS Roland B. Day, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application February 8, 1932, Serial No. 591,503

3 Claims.

treatment of cracked hydrocarbon distillates of gasoline boiling range though straight run distillates of similar character and of higher boiling range than gasoline may also be treated. Cracked distillates frequently contain large amounts of gum-forming constituents such as the diand tri-olefins and of sulfur compounds which include representatives of various groups such as mercaptans, thioethers, thiophenes, etcetera, along with considerable percentages of hydrogen sulfide.

The present invention is directed to the treatment of cracked hydrocarbon oil vapors for the removal of the gum-forming and sulfur compounds mentioned and possesses the advantages of ready applicability, ease of operation and low cost in comparison with existing processes.

In a more specific sense the invention has reference to a process for the treatment of hydrocarbon oil in heated vaporous condition whereby the distillates resulting from the subsequent fractionation of said vapors are so refined and stabilized that further chemical treatment may not be necessary to fit them for consumption, and if any further treatment is necessary, it is only of a minor character.

In one specific embodiment the invention comprises treating hydrocarbon oils, particularly cracked hydrocarbon oil distillates while in heated vaporous condition, with hydrochloric acid and/or other halogen acids while in contact with metal salt mixtures comprising both metals above and metals below hydrogen in the electro-- chemical series.

The attached diagrammatic drawing indicates in side elevation a particular arrangement of plant equipment which may be employed, though the invention is not limited thereto.

Referring to the drawing, the apparatus will be seen to consist of a treater 7-in which the solid contact materials may be disposed in the best manner for afiording intimate contact of the mixture of halogen acid and oil vapors therewith, a fractionator 27 for final rectification of the treated vapors and the usual condensing and collecting equipment.

Oil vapors to be treated may be admitted to the system through a line 1, containing a control valve 2, permitting reduction or release of (Cl. 196-36) This invention relates more particularly to the pressure if it be found advantageous to employ lower pressures than those under which the vapors have been generated. Since either upward or downward flow of the vapors and acid over the solid contact materials may be employed, treater 7 is shown provided with the necessary lines for permitting either type of flow. When downflow treatments are to be conducted, the entering vapors may be passed through a line 3, containing a control valve 4, to upper vapor space 9 above the bed of contact material 8, and when upflow treatments are more suitable for any reason, the vapors may be diverted through line 5, containing control valve 6 and enter low vapor space 10 below the perforated support 8'. The halogen acid employed may also be admitted to either the upper or lower vapor spaces of the treater and since this acid will be hydrochloric in the majority of cases unless minor amounts of the other halogen acids are considered, the description will refer to this acid as an example. To provide for admission of the acid to the system, a line 13, containing a control valve 14, is shown, this line branching into line 15, containing control valve 16, and terminating in distributing means 16' and 17, containing control valve 18, and terminating in distributing means 18'.

The acid may be introduced as the anhydrous gas or as a solution of varying concentration, though in upfiow treatments it may at times be preferable to utilize the gas instead of the solution for reasons of distribution. In either event the mixture of hydrocarbon oil vapors and hydrochloric acid in proper amount are introduced to the treater and caused to flow upwardly or downwardly over the contact materials. Since these materials constitute an important part of the present invention, they will be described in some detail.

While various modifications in the character of the solids may be employed, the essential point is that the mixture shall contain a salt of at least one metal above hydrogen in the electrochemical series and the salt of one metal below hydrogen in the electrochemical series. A list of metals is appended in the order of their diminishing tendency to enter the ionic from the elementary state, those above hydrogen in the list being known as electro-positive metals and those below hydrogen as electro-negative.

Electrochemical series of metals Hydrogen Antimony Bismuth Arsenic Copper Mercury Silver Platinum Gold The salts employed may be those of acids of widely different character, and they may be chosen or previously prepared to present the greatest possible contact surface so that the rate of the reactions is accelerated. The salts may be utilized as such in proper admixture or they may be employed in a more disseminated state by incorporation with or deposition upon relatively inert filling or spacing materials such as fullers earth, silica, clays, etcetera. In some cases it may be advantageous to incorporate the properly proportioned salts with materials of a definitely cementitious character. be mixed with such materials as natural and Portland cement, litharge and glycerine, zinc and other oxychlorides, et cetera, the proportionpf cementing substance and the subsequent treatment of the composite mass being so regulated that an extending surface is presented and the particles have a minimum tendency to disintegrate under the conditions to which they are exposed.

Other solid contact materials which may be employed consist of naturally occurring ores or minerals containing electro-positive and electronegative metals. As typical of mixtures which may be employed, ores of zinc representing metals above hydrogen and ores of copper representing metals below hydrogen may be mentioned, though it will be understood from a consideration of the list of metals given above that many other metal combinations are possible. Furthermore, the ores may be sulfide ores, silicate ores or basic carbonates and it may frequently happen that the gangue materials present may act as spacing agents and further assist in presenting the metal salts as an extended surface.

Referring to zinc ores, the sulfide ore of zinc may at times be used, this ore being known as sphalerite or zinc blende. Ores of this character frequently contain traces of iron and manganese and sometimes cadmium and mercury. The iron at times may run as high as 18%, being present in isomorphus mixture with the zinc. In general, sulfide ore is not as efficient as the other ores For example, they may presently to be mentioned but may possess at times a long period of moderate activity which renders its use practical.

Of the silicate ores, several may be mentioned. Willemite or Troostite occur with siliceous gangue material as zinc ortho silicate having the formula Zn2SiO4. These minerals may also contain iron and manganese partially replacing the zinc.

Another zinc silicate ore is the well-known Calamine having the -general formula HzZnzSiOs 0r HaO.2ZnO.SiOz.

Among the zinc carbonates may be mentioned Smithsonite having the formula ZnCOa. This mineral is frequently associated with other carbonate minerals such as the carbonates of iron and manganese and it occurs frequently with galena and sphalerite.

Another zinc ore of a combined carbonate and hydroxide character is Aurichalcite 2(Zn, Cu)

COa.3(Zn, Cu) (OH)2.

Still another of this type of ore is Hydrozincite, ZnCO3.2Zn(OH)a or 2ZnO.COz.2H2O. This particular mineral is a variety of Smithsonite and frequently occurs with it.

Referring to the ores of copper, the sulfide Chalcocite having the formula CuzS may be mentioned. Also, the double sulfide Stromeyerite Ag2S.Cl12S may be mentioned as possessing the particular advantage in some cases of containing two metals below hydrogen in the electrochemical series.

Among the silicate ores of copper may be mentioned those containing the mineral Dioptase having the formula H2Cl1SiSO4 or H2O.Cl1O.SiO2. This mineral occurs in the copper mines of Clifton, Graham County, Arizona, in crystals lining cavities in the ore deposits, usually in association with oxides of iron and copper. The occurrence of copper as a basic carbonate is very common and ores containing these carbonates are readily utilizable. Among the carbonates of copper which occur in nature may be mentioned Malachite or basic cupric carbonate CLICO3.CL1(OH)2 or 2CU.O.CO2.H2O. This compound occurs in the ores of New Mexico and Utah in large amounts. Another well known copper mineral of common occurrence is Azurite or basic cupric carbonate CuCOa.Cu(0H)2 or 2C11O.CO2.H2O. It will be observed that the ultimate chemical composition of these two copper carbonate minerals is the same, the difierence being in crystal structure.

The above examples of ores both in the case of zinc and copper are cited merely as illustrations of the various types of ores which may be employed. There are many other combinations possessing varying degrees of effectiveness and the choice of an ore or mixture of ores for contact materials for use in the process will be determined by consideration of availability, cost and varying efficiency which may be evidenced in their use both as to their primary efiiciency and to the life of the mass when used over extended periods of time.

The contact masses (which are only limited to the fact that they must contain a compound or .salt of a metal above and below hydrogen respecdisintegration or sintering. Furthermore, naturally occurring ores may be mixed with artificially prepared salts and these composite mixtures worked up in any suitable manner to produce the contact masses. In any case the value of any contact mass employed will not be exactly equivalent to the value of those produced by other combinations of salts comprised within the scope of the invention.

The contact materials may be employed in space 8 of treater 'l as a substantially uniform mass of proper sized particles to afiord contact without unnecessary resistance to flow or they may be employed in layers of alternating or progressively varying composition or supported upon regularly spaced trays. When downfiow treatments are conducted a certain amount of condensation may occur although this may be prevented if found desirable by preliminary superheating of the vapors or heating the treater to prevent drop in temperature. When upflow treatments are conducted, a certain amount offractionation may occur if no special precautions are taken to prevent condensation. In any event the conditions of operation in the treater will be regulated to produce the desired results. The treater is shown provided with manheads 11 and 12 for admission of contact materials and for their rejection when spent.

Vapors resulting from upflow treatments may be passed from the treater through line 19, containing control valve 20, and either passed directly, if sufficiently fractionated, to a condenser through line 23, containing control valve 24, and line 30, containing control valve 31 or, if further fractionation appears advantageous or desirable, they may be diverted through line 25, containing control valve 26, and enter the fractionator through line 21, containing control valve 22.

Vapors from downflow treatments may undergo a rough preliminary separation into vapors and non-vaporized liquids consistng of hydrocarbon oil polymers and derivatives and other reaction products, the vapors being passed to the fractionator through line 19', containing control valve 20', and the oils and other liquids being conducted from the bottom of the vapor chamber through line 45, containing control valve 46, to accumulator 47. This accumulator may have a line 48 connecting it with the vapor space of the treater to prevent gas lock. The liquid accumulations comprising those already described and the refluxes from fractionator 27 entering the accumulator from line 49, containing control valve 50. may be withdrawn therefrom through a line 51, containing control valve 52, and pumped by a pump 53 through a line 54, containing control valve 55, to any suitable point of disposal.

Vapors from fractionator 27 may pass through line 28, containing control valve 31, to condenser 32 which serves the purpose of liquefying gasoline fractions and cooling fixed gases, the mixture passing through line 33, containing control valve 34, to receiver 35. From this point the fixed gases may be withdrawn through line 36, containng control valve 37, at a rate consistent with the maintenance of suitable back pressure upon preceding portions of the equipment and the treated gasoline constituting the end product of the process may be withdrawn to storage or other mild final treatment through line 38, containing control valve 39. To assist in controlling the boiling point range of the vapors from the fractionator, a suitable portion of the end product liquids may be returned to the top of the fractionator, these portions being led to recirculating pump 42 through line 40, containing control valve 41, and discharged therefrom through line 43, containing control valve 44.

I have found that the use of contact materials as described produces particularly good results in the treatment of hydrocarbon vapors to reduce gum-forming constituents and sulfur compounds. It will be evident that owing to the wide range in composition of the contact mass that it may be proportioned to give treatments of a more distinctly polymerizing character or of a more pronounced desulfurizing action. Thus, in general, when polymerization is the main object as may occur when treatingcracked vapors produced from parafiinic charging stocks of low sulfur content, the masses may contain relatively larger proportions of compounds of electro-positive metals such as zinc or tin, whose chlorides have known polymerizing value. When a desulfurizing treatment is necessary the proportion of electronegative metal such as copper, silver, etcetera, may be somewhat increased. To account for the desulfurizing tendency of the contact masses thus employed in the presence of hydrochloric acid, it may be presumed that while the sulfur in organic combinations has greater aflinity for the electronegative metal and that corresponding sulfides are formed as intermediate products, these are decomposed due to the joint action of hydrochloric acid and the chloride of the electro-positive metal, to liberate hydrogen sulfide. While this theory may not be entirely adequate to explain the complex reactions that are probably involved, the observations are definite to the effeet that greater desulfurization is accomplished when using contact masses of the character described than when using compounds of electropositive or electro-negative metals alone.

Further advantage of the process appears in that the rate of consumption and depreciation of the contact masses may be largely controlled by choice of proper salts and proportioning them to prevent too rapid penetration of the hydrochloric acid and oil vapors into the particles of the mass. Thus, while in some instances it may be unavoidable that chlorides like those of zinc and tin may be gradually dissolved and removed from the sphere of the reaction to appear as a solution or slime in the bottom of the treater, the rate of this action may be reduced and the period of usefulness of the contact mass extended by suitable choice of materials according to the present process.

While a considerable number of examples of results obtainable by the operation of the process might be given, a few will suflice to indicate the commercial advantages of the process.

For treating vapors of approximate gasoline boiling point range from the fractionator of a cracking plant operating upon Pennsylvania gas oil, a contact mass may be made up composed of approximately equimolecular proportions of zinc and cupric chlorides, these being mixed with relatively coarse (20 mesh) fragments of fullers earth constituting about by weight of the total mass. The temperature of the vapors entering the treater may be approximately 300 F. and their pressure about 50 pounds per square inch, hydrochloric acid being used at the rate of about 1% pounds per barrel of finished product and a suitable vapor velocity being maintained to insure completion of the treating reactions. The gasoline condensed from the vapors subjected to this treatment may have the properties shown in the treated column, while the corresponding properties of a gasoline produced by simple fractionation without chemical treatment are shown in the untreated" column, the yield being the same in both cases.

Gravity A.P.I End point F A case may also be considered in which the contact mass is made up of silicate ores of zinc and copper, respectively, these being blended so as to give approximately equal weights of zinc and copper, and the gangue materials supplemented by the addition of approximately 10 to 20 mesh silica fragments. In a case of this character it may be well to use a solution of hydrochloric acid in place of the anhydrous gas to more efiectively activate the zinc and copper minerals-by partially decomposing them with the hot acid in liquid phase. When such a mass is used upon gasoline boiling range vapors produced from cracking a heavy Mid-Continent gas oil using approximately two pounds of hydrochloric acid per barrel of finished gasoline, it may be possible to produce by one vapor phase treating operation a gasoline suitable in all respects for immediate marketing or storage without deterioration of properties, provided the freshly condensed gasoline is given alight caustic wash. The appended table again shows the comparative properties for the same yield of the untreated and treated gasolines.

- From the two preceding examples it wifl be readily apparent that the process is one of great value. However, these examples are illustrative merely and are not to be construed as imposing limitations upon the generally broad scope of the .80 invention, since many other typesof cracked vapors as well as vapors of straight run gasoline may be treated. Furthermore, the exact details of the descriptive portion of the specification are not to be similarly construed as the operation described is also merely illustrative.

I claim as my invention:

1. In a process for refining hydrocarbon oil to remove color and gum forming components and to reduce the sulphur content thereof, the improvement which comprises subjecting said hydrocarbon oil in heated condition to the action of hydrochloric acid while in contact with a solid mixture of a salt of a metal above and a salt of a metal below hydrogen in the electro-chemical 98 series. 1

' 2. In a process for. refining hydrocarbon oil to improve its characteristics by removing color and gum forming components and to reduce the sulphur content thereof, the improvement which 100 comprises subjecting the said hydrocarbon oil while in heated vaporous condition to the action of hydrochloric acid while in contact with a solid mixture of a salt of copper and a salt of zinc.

3. In a process for refining hydrocarbon oil to improve its characteristics by removing color and gum forming components and to reduce the sulphur content thereof, the improvement which comprises subjecting the said hydrocarbon oil while in heated condition to the action of hydrochloric acid in the presence of a solid mixture of a salt of copper and a salt of zinc.

ROLAND B. DAY. 

